As and Cd in soil can be assimilated and accumulated by vegetables and can be subsequently ingested by humans. Contradictory effects of organic fertilizer application on As and Cd accumulation in soil have been reported in previous studies. An eight-year greenhouse study was conducted on a sandy loam soil in Beijing, China to investigate the effects of organic fertilizer application rate on soil properties, and As and Cd accumulation in soil. The contamination risk of pak choi grown after eight years’ application of organic fertilizer was also evaluated. Soil organic carbon increased 3.0–3.8 times with low, medium and high rates of fertilizer application in 2018 compared to the initial soil. Organic fertilizer application significantly increased soil nutrients and microbial biomass while it mildly affected soil pH. The bioavailability of As/Cd has decreased after eight years’ application of organic fertilizer. Pak choi crop harvested from all three treatments in 2018 did not pose a threat to human health, even for life-time consumption. Soil total As content significantly decreased with organic fertilizer application, mainly due to the lower As content in the applied fertilizer than that in soil. Continuous application of clean organic fertilizer can be adopted to reduce the contamination risk of highly contaminated soil in the soil–plant system.

Sustainable intensification of protected vegetable crops entails increasing yield while reducing environmental impact and labor input. To explore a comprehensive strategy for high yielding, highly efficient and high quality production of greenhouse tomato (Solanum lycopersicum L.), an integrated crop-nitrogen management (ICNM) strategy was compared to farmers’ traditional management (TM) in a field experiment in a solar greenhouse. A split-plot block design was used. The main factor was the management strategy of ICNM and TM. The secondary factor was four different basal fertilizer treatments, being a control (CK; 0 kg N ha⁻¹), carbon-based urea (BU; 100 kg N ha⁻¹), controlled release urea (CU; 100 kg N ha⁻¹), and conventional compound fertilizer (CF; 100 kg N ha⁻¹). An additional 200 kg N ha⁻¹ through drip irrigation as topdressing was used. Tomato fruit yield, N uptake, and N partial productivity with ICNM were significantly higher than with TM, increasing by 32.1%, 39.7%, and 31.1%, respectively. The proportion of fine roots was increased in ICNM, and the average diameter of roots decreased by 10.7% compared to TM. There was a significant negative correlation between mean root diameter and N uptake. In conclusion, the ICNM strategy was beneficial to form a good root system configuration, promote the development of shoot biological potential, increase tomato yield, maintain fruit quality, increase N uptake, and reduce environmental risks.

Considerable nitrogen (N) losses from intensive vegetable systems have become an important source of environmental damage. A high-efficiency N application to minimize N pollution and improve production is urgently needed. Here, we conducted field experiments to identify the effects of a single application of controlled-release urea (CRU), conventional urea (CU), and chicken manure (CM) on N losses and yields improvement in a greenhouse tomato system in Beijing, China. Five treatments were carried out: no N control (CK), lower rate of CRU with CU and CM (CRN1), medium rate of CRU with CU and CM (CRN2), higher rate of CRU with CU and CM (CRN3), and conventional fertilization (CN). The results showed that the single application of CRU, CU, and CM reduced the nitrate N concentration and N₂O emissions by 22 to 79% and 39 to 51%, respectively, compared with the conventional fertilization . Based on the N application rate, the average nitrate N concentration showed an exponential increase, and the cumulative N₂O emissions showed a linear increase. Compared to the CN treatment, the CRN1, CRN2, and CRN3 treatments decreased fertilization cost by 44%, 22%, and 3.4%, while raising yields by 9.6%, 17%, and 2.0%, respectively. The apparent N surplus of the CRN1 and CRN2 treatments was reduced by 39% and 13% relative to the CN treatment, whereas the CRN3 treatment was as high as that of the CN treatment. It can be concluded that applying CRU, CU, and CM at the higher rate hardly improved the yield but increased the risk of N losses, whereas the lower and medium rates of CRU could reduce N pollution and improve production. The CRN2 treatment, reducing the CRU rate by 25%, with the highest economic efficiency, was the best choice to achieve greater yields with less environmental impacts in greenhouse tomato systems. Abbreviations: CRU, controlled-release urea; CU, conventional urea; CM, chicken manure; DAT, days after transplanting.

Introduction: Improvement of root architecture is crucial to increasing nutrient acquisition.Methods: Two pot experiments were conducted to investigate the effects of different concentrations of urea ammonium nitrate solution (UAN) and ammonium polyphosphate (APP) on lettuce root architecture and the relationship between roots and nitrogen (N) and phosphorus (P) absorption.Results: The results showed that lettuce yield, quality, and root architecture were superior in the APP4 treatment compared to other P fertilizer treatments. The N480 treatment (480 mg N kg^-1 UAN) significantly outperformed other N treatments in terms of root length, root surface area, and root volume. There were significant quantitative relationships between root architecture indices and crop uptake of N and P. The relationships between P uptake and root length and root surface area followed power functions. Crop N uptake was significantly linearly related to the length of fine roots with a diameter of <0.5 mm.Conclusion and discussion: The length of fine roots played a more prominent role in promoting N absorption, while overall root size was more important for P absorption. APP has a threshold of 9.3 mg P kg^-1 for stimulating the root system. Above this threshold, a rapid increase in root absorption of P. UAN can promote extensive growth of fine roots with a diameter less than 0.5 mm. Applying appropriate rates of APP and limiting UAN application to less than 400 mg N kg^-1 can improve root architecture to enhance N and P absorption by lettuce. These results highlight a new possibility to improve nutrients use efficiency while maintaining high yields.

Pectobacterium is one of the most important genera of phytopathogenic bacteria. It can cause soft-rot diseases on a wide range of plant species across the world. In this study, three Pectobacterium strains (KC01, KC02, and KC03) were isolated from soft-rotted Chinese cabbage in Beijing, China. These three strains were identified as Pectobacterium versatile based on phylogenetic analysis of Pectobacterium 16S ribosomal RNA, pmrA, and 504 Pectobacterium core genes, as well as a genomic average nucleotide identity analysis. Their biochemical characteristics were found to be similar to the P. versatile type strain ICMP9168^T but differed in response to citric acid, stachyose, D-glucuronic acid, dextrin, and N-acetyl-β-D-mannosamine. All of the tested P. versatile strains showed different carbohydrate utilization abilities compared with P. carotovorum and P. odoriferum, particularly in their ability to utilize D-arabitol, L-rhamnose, and L-serine. Under laboratory conditions, the maceration ability of P. versatile on Chinese cabbage was the highest at 28°C, compared with those at 13, 28, 23, and 33°C. Additionally, P. versatile could infect all of the 17 known Pectobacterium host plants, except for Welsh onion (Allium fistulosum). A SYBR Green quantitative PCR (qPCR) detection system was developed to distinguish P. versatile from other soft-rot bacteria based on the combined performance of melting curve (with a single melting peak at around 85°C) and fluorescence curve (with cycle threshold <30) when the bacterial genomic DNA concentration was in the range of 10 pg/µl to 10 ng/µl. This study is the first to report the presence of P. versatile on Chinese cabbage in China, as well as a specific and sensitive qPCR assay that can be used to quickly identify P. versatile. The work contributes to a better understanding of P. versatile and will facilitate the effective diagnosis of soft-rot disease, ultimately benefitting commercial crop production.

In the cold and arid regions of northern China, efficient water and nitrogen (N) management is critical for the sustainable production of leafy vegetables. Simplified models that estimate crop N and water transpiration demands using simple inputs based on climate parameters become an important method for making precise suggestions on N and irrigation application at a regional scale. This study developed and validated a regionally adapted version of the VegSyst model, named VegSyst-CH, based on a multi-year open-field experiment from 2021 to 2023. Model parameters were calibrated using data from the 2021 growing season and validated with independent datasets from 2022 and 2023. A critical N concentration (CNC) curve was established to describe the relationship between biomass accumulation and N content. VegSyst-CH, with a radiation use efficiency of 1.94 g MJ⁻¹, demonstrated high simulation accuracy for crop growth. The model showed a good predictive performance of N uptake under medium (N1) and high (N2) N treatments, with coefficients of determination (R²) above 0.80 across years and normalized root mean square error (NRMSE) values generally below 30%. The VegSyst-CH model also showed high accuracy in simulating crop evapotranspiration (ETc) over three consecutive growing seasons (2021–2023), with the dynamic trends of cumulative ETc closely aligning with measured values and the coefficients of determination (R²) consistently exceeding 0.90. These results validate the model’s robustness and applicability across different years. In conclusion, the VegSyst-CH model has strong spatiotemporal regulation capacity and climatic responsiveness, offering a robust decision support tool for precision fertilization and irrigation in open-field lettuce production in cold and arid regions.